New York onion growers can reduce their use of synthetic chemicals while maintaining yields, research shows

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Used in cuisines around the world, onions are known for either their sweet and savory flavor or their strong and pungent flavor that enhances dishes from casseroles to curries. Consumers in the US eat a lot of onions – that vegetables According to the Cornell Chronicle, potatoes, tomatoes and sweetcorn are lagging behind in popularity.

Onion bulbs can be grown in almost any part of the country, Brian A. Nault, a professor of entomology at Cornell AgriTech, told EcoWatch in an email.

Nault is the lead author of a new to learn“Impact of Reducing Synthetic Chemical Inputs on Pest and Disease Management in Commercial Onion Production Systems,” published in the journal agronomy.

Nault told EcoWatch that most onions produced in America are grown in Washington, Oregon, California and eastern Idaho. On the East Coast, onion production is concentrated in New York and Georgia.

They may be easy to grow, but onions are also susceptible to common insects that enjoy them as much as we do.

“When the leaves of onions expand, tiny creatures can find them onion thripswho suck juice from onion leaves. These are difficult to spot because they hide in the folds and neck of the leaves,” Bonnie Plants warned.

Not only do thrips consume the bulb plants, but they also carry a virus that can kill bulbs and spread bulb-rotting bacteria, the Cornell Chronicle reported.

According to SFGATE, natural methods — like spraying the plants with water, surrounding plants with mulch, planting crops like vegetables, herbs, and flowers around the bulbs, or using a nitrogen-based fertilizer — can be used to deter thrips.

Nault told EcoWatch that the natural methods he and his team tested have not proven as effective as synthetic chemicals at keeping onion thrips population numbers down.

“Members of my research program and I have investigated many natural alternatives to synthetic pesticides for controlling onion thrips in onions that may be more environmentally friendly. Unfortunately, none have proven to be as effective as some [of] the best synthetic pesticides except Spinosad (Entrust SC) which is an OMRI listed product that can be used in organic onion production. We evaluated reflective mulch, straw mulch, bulbs bred to suppress thrips, and naturally occurring biological control. In some cases, we’ve seen a slight reduction in onion thrips density using these alternative practices, but in most cases they’ve either failed or been inconsistent,” Nault said.

The study found that when farmers used “intervention thresholds” ⁠ – the density level of a crop pest at which the population must be controlled to keep it at a level that does not result in economic losses ⁠ – and applied insecticides 2.3 fewer times to control onion thrips; Onion bulb size and yields were maintained, the Cornell Chronicle reported.

After three years of field trials, the researchers found that 50 to 100 percent less fertilizer could be used without reducing crop yields.

“Plots without fertilizer had no difference [compared to plots with full and half amounts]said Max Torrey, whose 12th-generation family farm in Elba, New York, was one of the study’s experimental sites, the Cornell Chronicle reported. “People were skeptical, but this evidence gives us a lot more confidence in what to use.”

Almost all of New York’s 7,000 acres of dry onions are grown in the fertile “dirt soil” of drained swamps. The climate of western New York requires rigorous cultivation for growing onions, and farmers use many synthetic chemicals such as pesticides and fertilizers on their onion crops.

“Mold soil is an excellent type of soil for growing onions. However, there are other types of soil that are very suitable for growing onions (e.g. sandy soils). For example, most onions grown in the western US are not grown in clay soils,” Nault told EcoWatch. “[M]Much less synthetic fertilizer is needed to grow onions in clay soil, but eliminating fertilizer altogether is unlikely to be the solution in the long run.”

Although onion growers in New York have a geographic advantage being close to major East Coast markets, demand, growing conditions, pests and diseases all play a role in their profits each year, the Cornell Chronicle reported.

“[T]he use of synthetic chemicals [is] still necessary for most NY onion growers to produce a profitable onion crop. This is especially true for the large-scale commercial production of onions as they are grown in large monocultures and there are many weeds, insects and diseases that negatively affect onions,” Nault told EcoWatch.

Nault said that beginning in the late 1990s, onion growers became more reliant on insecticide spraying programs to keep onion thrips numbers down, the Cornell Chronicle reported. Then thrips quickly became resistant to the pesticides.

In order to maintain the effectiveness of the insecticides still in use, Nault has adjusted the effect thresholds so that onion growers in New York can only spray when needed and still remain profitable.

“By reducing the frequency of insecticide applications in general, and the use of each insecticide in particular, resistance development in thrips populations should be mitigated. Essentially, the goal is to minimize the chance that an onion thrips will mutate, giving it the ability to resist a particular insecticide active ingredient,” Nault told EcoWatch. “Let me use a baseball analogy. If a pitcher only throws fastballs to a hitter, that hitter will eventually learn to hit a fastball. However, if you throw fastballs, sliders, change-ups, splitters, etc. and mix them up when throwing at the batter, the batter has a much lower chance of hitting one of the balls. And if you never pitch the ball, the batsman can’t hit it!”

Insecticide resistance is so widespread that it encourages farmers to use action thresholds in their crop management practices.

“The primary reason farmers cite for using action thresholds is to mitigate the development of insecticide resistance,” Nault said in the Cornell Chronicle. “The next new good chemical tool might not come until 2025. You can’t afford to lose this one.”

Nault discovered studies showing that using less fertilizer had the potential to reduce the number of pests in some crops and decided to include this factor in the study’s testing trials.

Nault and the onion growers involved in the study found that it doesn’t matter how much fertilizer was applied to an onion at the time of planting. The number of thrips, bulb size, bulb blight and total yield were not affected.

“We didn’t expect that, but it has an even bigger potential impact,” Nault said, as reported by the Cornell Chronicle. “Reducing fertilizer use in commercial agriculture is beneficial to the environment for so many reasons, most notably water and soil health.”

Each year, New York onion growers could save $420,000 in pesticide costs by using action thresholds, Nault said. Nault has seen a number of onion growers reduce their use of fertilizer from 25 percent to 50 percent, rather than applying a standard amount to each field.

“[T]The most effective product order was combined with the use of action thresholds to optimize onion thrips control. Instead of spraying onions with insecticides weekly, onion growers have significantly reduced the number of applications,” Nault told EcoWatch.

The use of fewer synthetic chemicals in onion crops has a number of environmental benefits.

“Reducing the use of synthetic pesticides can benefit the environment by preserving non-target organisms. Examples can be beneficial insects that feed on insect pests that live either above or below ground. In some cases, reducing the use of pesticides can improve soil health by preserving soil microorganisms and arthropod fauna. Other benefits could include reducing the runoff of pesticides into water systems that could be harmful to aquatic organisms,” Nault said.

Torrey explained that although sampling soil and looking for thrips requires more work, he expects to save at least $100 per hectare in synthetic chemical costs on 2,200 acres of onion crops, not to mention the benefits it will bring to the environment has. The Cornell Chronicle reported.

“The crap is our livelihood and our future,” Torrey said in the Cornell Chronicle. “We have to take care of it. Now we finally have a proven way to cut costs and make New York onion growers even more competitive and sustainable.”

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